What Does Cortisol Do?

Many people wonder what cortisol does since cortisol and stress are so closely related. A simple answer is that the purpose of cortisol is as a stress hormone in the body and its primary purpose is to breakdown body tissues to be used as an energy source.

Whenever the body is put under stress, no matter whether it is psychological stress or physical stress, the body responds by producing cortisol. Cortisol also gets produced in response to a low blood sugar level.

Cortisol's primary functions are to:

• Increase the blood sugar level
• Suppress the immune system
• Promote fat, protein and carbohydrate metabolism

Cortisol is released from the cortex (outer portion) of the adrenal glands and is sent into the bloodstream. It targets the liver, muscles, skin, adipose tissue and lymphatic system.

What does cortisol do in the liver?

In the liver it promotes 'gluconeogenesis', which is the creation of glucose from amino acids (protein) and glycerol (the backbone of triglycerides).

What does cortisol do in the muscles?

In the muscles it promotes the breakdown of lean tissue to liberate amino acids. These amino acids then go to the liver to go through the process of gluconeogenesis, which will raise the blood sugar (glucose) level.

What does cortisol do in the skin?

In the skin cortisol promotes vasoconstriction, which is constriction of the blood vessels. This is an evolutionary response whereby if we are ever faced with a physical conflict, if we are cut we are less likely to bleed excessively because of the restricted blood flow to the skin.

What does cortisol do in the adipose tissue (fat)?

In the adipose tissue, cortisol promotes the breakdown of fats into fatty acids and glycerol. The glycerol may then be sent to the liver to contribute to gluconeogenesis and raise blood sugar levels.

What does cortisol do to the immune system?

Cortisol is also known to suppress immune responses in many body tissues, especially inflammatory responses.

Overall, from a weight loss perspective it is important to keep cortisol in check. Even though it does promote the breakdown of fats in the body, since it raises glucose levels in the blood stream, it also contributes to insulin resistance. It also contributes to insulin resistance by decreasing the translocation of GLUT4 receptors to the cell membranes.

Plus, the loss of muscle that results from the production of cortisol and therefore, the resulting metabolism depression, far outweigh the fat breakdown that occurs. Furthermore, high cortisol levels increase the conversion of T4 into rT3, which puts a 'brake' on all cellular metabolism. To find out more about the impact of cotisol on thyroid hormones, read, Low Thyroid Symptoms.

Finally, cortisol is a steroid hormone, which means it comes from the same basic compound as other steroid hormones in the body, pregnenolone. Since the body produces a limited amount of pregnenolone, if it is used for cortisol production, less is left over for the other steroid hormones that have potent fat-burning abilities like, testosterone or progesterone.

In saying this, it is important not to have cortisol too low either because a small amount is required for optimum thyroid functioning. Cortisol is said to have a 'refreshing effect' on cell membranes, which keeps the cells fully receptive to the action of thyroid hormones. This is discussed in more detail in the article, Thyroid Disease Symptoms.

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